dendrite/publicroomsapi/directory/public_rooms.go
Kegsay 97c64bdb6d
p2p: de-dupe and shuffle public rooms; implement keydb (#1074)
- We don't want a serverKeyAPI as fetching keys doesn't need a DB.
- De-dupe rooms so we don't see them multiple times, but shuffle the
  alias we join via so we don't all flood a single server.
2020-05-29 15:34:15 +01:00

256 lines
8.6 KiB
Go

// Copyright 2017 Vector Creations Ltd
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package directory
import (
"context"
"math/rand"
"net/http"
"strconv"
"sync"
"time"
"github.com/matrix-org/dendrite/clientapi/httputil"
"github.com/matrix-org/dendrite/clientapi/jsonerror"
"github.com/matrix-org/dendrite/publicroomsapi/storage"
"github.com/matrix-org/dendrite/publicroomsapi/types"
"github.com/matrix-org/gomatrixserverlib"
"github.com/matrix-org/util"
)
type PublicRoomReq struct {
Since string `json:"since,omitempty"`
Limit int16 `json:"limit,omitempty"`
Filter filter `json:"filter,omitempty"`
}
type filter struct {
SearchTerms string `json:"generic_search_term,omitempty"`
}
// GetPostPublicRooms implements GET and POST /publicRooms
func GetPostPublicRooms(
req *http.Request, publicRoomDatabase storage.Database,
) util.JSONResponse {
var request PublicRoomReq
if fillErr := fillPublicRoomsReq(req, &request); fillErr != nil {
return *fillErr
}
response, err := publicRooms(req.Context(), request, publicRoomDatabase)
if err != nil {
return jsonerror.InternalServerError()
}
return util.JSONResponse{
Code: http.StatusOK,
JSON: response,
}
}
// GetPostPublicRoomsWithExternal is the same as GetPostPublicRooms but also mixes in public rooms from the provider supplied.
func GetPostPublicRoomsWithExternal(
req *http.Request, publicRoomDatabase storage.Database, fedClient *gomatrixserverlib.FederationClient,
extRoomsProvider types.ExternalPublicRoomsProvider,
) util.JSONResponse {
var request PublicRoomReq
if fillErr := fillPublicRoomsReq(req, &request); fillErr != nil {
return *fillErr
}
response, err := publicRooms(req.Context(), request, publicRoomDatabase)
if err != nil {
return jsonerror.InternalServerError()
}
if request.Since != "" {
// TODO: handle pagination tokens sensibly rather than ignoring them.
// ignore paginated requests since we don't handle them yet over federation.
// Only the initial request will contain federated rooms.
return util.JSONResponse{
Code: http.StatusOK,
JSON: response,
}
}
// If we have already hit the limit on the number of rooms, bail.
var limit int
if request.Limit > 0 {
limit = int(request.Limit) - len(response.Chunk)
if limit <= 0 {
return util.JSONResponse{
Code: http.StatusOK,
JSON: response,
}
}
}
// downcasting `limit` is safe as we know it isn't bigger than request.Limit which is int16
fedRooms := bulkFetchPublicRoomsFromServers(req.Context(), fedClient, extRoomsProvider.Homeservers(), int16(limit))
response.Chunk = append(response.Chunk, fedRooms...)
// de-duplicate rooms with the same room ID. We can join the room via any of these aliases as we know these servers
// are alive and well, so we arbitrarily pick one (purposefully shuffling them to spread the load a bit)
var publicRooms []gomatrixserverlib.PublicRoom
haveRoomIDs := make(map[string]bool)
rand.Shuffle(len(response.Chunk), func(i, j int) {
response.Chunk[i], response.Chunk[j] = response.Chunk[j], response.Chunk[i]
})
for _, r := range response.Chunk {
if haveRoomIDs[r.RoomID] {
continue
}
haveRoomIDs[r.RoomID] = true
publicRooms = append(publicRooms, r)
}
response.Chunk = publicRooms
return util.JSONResponse{
Code: http.StatusOK,
JSON: response,
}
}
// bulkFetchPublicRoomsFromServers fetches public rooms from the list of homeservers.
// Returns a list of public rooms up to the limit specified.
func bulkFetchPublicRoomsFromServers(
ctx context.Context, fedClient *gomatrixserverlib.FederationClient, homeservers []string, limit int16,
) (publicRooms []gomatrixserverlib.PublicRoom) {
// follow pipeline semantics, see https://blog.golang.org/pipelines for more info.
// goroutines send rooms to this channel
roomCh := make(chan gomatrixserverlib.PublicRoom, int(limit))
// signalling channel to tell goroutines to stop sending rooms and quit
done := make(chan bool)
// signalling to say when we can close the room channel
var wg sync.WaitGroup
wg.Add(len(homeservers))
// concurrently query for public rooms
for _, hs := range homeservers {
go func(homeserverDomain string) {
defer wg.Done()
util.GetLogger(ctx).WithField("hs", homeserverDomain).Info("Querying HS for public rooms")
fres, err := fedClient.GetPublicRooms(ctx, gomatrixserverlib.ServerName(homeserverDomain), int(limit), "", false, "")
if err != nil {
util.GetLogger(ctx).WithError(err).WithField("hs", homeserverDomain).Warn(
"bulkFetchPublicRoomsFromServers: failed to query hs",
)
return
}
for _, room := range fres.Chunk {
// atomically send a room or stop
select {
case roomCh <- room:
case <-done:
util.GetLogger(ctx).WithError(err).WithField("hs", homeserverDomain).Info("Interrupted whilst sending rooms")
return
}
}
}(hs)
}
// Close the room channel when the goroutines have quit so we don't leak, but don't let it stop the in-flight request.
// This also allows the request to fail fast if all HSes experience errors as it will cause the room channel to be
// closed.
go func() {
wg.Wait()
util.GetLogger(ctx).Info("Cleaning up resources")
close(roomCh)
}()
// fan-in results with timeout. We stop when we reach the limit.
FanIn:
for len(publicRooms) < int(limit) || limit == 0 {
// add a room or timeout
select {
case room, ok := <-roomCh:
if !ok {
util.GetLogger(ctx).Info("All homeservers have been queried, returning results.")
break FanIn
}
publicRooms = append(publicRooms, room)
case <-time.After(15 * time.Second): // we've waited long enough, let's tell the client what we got.
util.GetLogger(ctx).Info("Waited 15s for federated public rooms, returning early")
break FanIn
case <-ctx.Done(): // the client hung up on us, let's stop.
util.GetLogger(ctx).Info("Client hung up, returning early")
break FanIn
}
}
// tell goroutines to stop
close(done)
return publicRooms
}
func publicRooms(ctx context.Context, request PublicRoomReq, publicRoomDatabase storage.Database) (*gomatrixserverlib.RespPublicRooms, error) {
var response gomatrixserverlib.RespPublicRooms
var limit int16
var offset int64
limit = request.Limit
offset, err := strconv.ParseInt(request.Since, 10, 64)
// ParseInt returns 0 and an error when trying to parse an empty string
// In that case, we want to assign 0 so we ignore the error
if err != nil && len(request.Since) > 0 {
util.GetLogger(ctx).WithError(err).Error("strconv.ParseInt failed")
return nil, err
}
est, err := publicRoomDatabase.CountPublicRooms(ctx)
if err != nil {
util.GetLogger(ctx).WithError(err).Error("publicRoomDatabase.CountPublicRooms failed")
return nil, err
}
response.TotalRoomCountEstimate = int(est)
if offset > 0 {
response.PrevBatch = strconv.Itoa(int(offset) - 1)
}
nextIndex := int(offset) + int(limit)
if response.TotalRoomCountEstimate > nextIndex {
response.NextBatch = strconv.Itoa(nextIndex)
}
if response.Chunk, err = publicRoomDatabase.GetPublicRooms(
ctx, offset, limit, request.Filter.SearchTerms,
); err != nil {
util.GetLogger(ctx).WithError(err).Error("publicRoomDatabase.GetPublicRooms failed")
return nil, err
}
return &response, nil
}
// fillPublicRoomsReq fills the Limit, Since and Filter attributes of a GET or POST request
// on /publicRooms by parsing the incoming HTTP request
// Filter is only filled for POST requests
func fillPublicRoomsReq(httpReq *http.Request, request *PublicRoomReq) *util.JSONResponse {
if httpReq.Method == http.MethodGet {
limit, err := strconv.Atoi(httpReq.FormValue("limit"))
// Atoi returns 0 and an error when trying to parse an empty string
// In that case, we want to assign 0 so we ignore the error
if err != nil && len(httpReq.FormValue("limit")) > 0 {
util.GetLogger(httpReq.Context()).WithError(err).Error("strconv.Atoi failed")
reqErr := jsonerror.InternalServerError()
return &reqErr
}
request.Limit = int16(limit)
request.Since = httpReq.FormValue("since")
return nil
} else if httpReq.Method == http.MethodPost {
return httputil.UnmarshalJSONRequest(httpReq, request)
}
return &util.JSONResponse{
Code: http.StatusMethodNotAllowed,
JSON: jsonerror.NotFound("Bad method"),
}
}